#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Date    : 2018-03-19 17:27:34


"""
import math


num = 81
t = 4
sum_list = []
while t != 0:
    t -= 1
    sum_list.append(num)
    num = math.sqrt(num)


# print(sum_list)
print('%.2f' % sum(sum_list))
"""
import math
import sys


def main(x):
    # x = map(int, raw_input().strip().split(' '))
    data = [x[0]]
    nums = x[1]
    for i in xrange(nums - 1):
        data.append(math.sqrt(data[-1]))
    print('%.2f' % sum(data))


input_data = []
while True:
    data = map(int, sys.stdin.readline().strip('\n').split())
    if len(data) == 0:
        break
    else:
        input_data.append(data)


for i in input_data:
    main(i)
